Plasma stripping, also known as plasma ashing, is a process of removing organic matter and/or residue, such as photoresist, from a workpiece during semiconductor processing. Typically, plasma stripping is performed using a plasma generator. Conventional plasma generators include a tube, a coil, and a processing gas source. The tube may be made of a dielectric material, such as quartz, and may be at least partially surrounded by the coil. An inner surface of the tube defines a plasma chamber that is in flow communication with the processing gas source to receive a processing gas therefrom. To diffuse the processing gas before injection into the plasma chamber, a gas flow distribution receptacle, also made of a dielectric material, may be disposed over an inlet to the plasma chamber. The gas flow distribution receptacle typically includes a ring of evenly spaced openings to provide a flow path between the processing gas source and the plasma chamber.
During operation, the coil is energized and creates an electric field across the plasma chamber. As the processing gas flows through the electric field within the plasma chamber, a portion of the processing gas becomes ionized and forms plasma. The plasma dissociates another portion of the processing gas and transforms it into reactive radicals. The reactive radicals flow to and deposit onto the workpiece, which is disposed adjacent to a dispersion plate or showerhead of the plasma chamber, and react with the organic matter and/or residue thereon to form an easily removable ash or other material.
Although the aforementioned system yields high quality results, the system may be improved. For example, in instances in which the processing gas includes fluorine-comprising gases, such as tetrafluoromethane (CF4), reactive fluorine radicals may be produced when the fluorine-comprising gas passes through the electric field. In some cases, the reactive fluorine radicals may chemically react with the quartz material of the gas flow distribution receptacle and/or the tube to cause erosion or etching thereof. In other cases, the chemical reaction may produce a silicon oxyfluoride (SiOF) film over the gas flow distribution receptacle and/or the tube. To avoid these unwanted effects, the gas flow distribution receptacle and/or tube are typically replaced once erosion is detected. However, some fluorine-comprising gases may erode or etch the components relatively quickly, and frequent replacement of these components may undesirably increase maintenance costs of the system.
Accordingly, it is desirable to have an improved plasma generator system that may be used in conjunction with fluorine-comprising processing gases such that the gases cause minimal etching of the system components. Additionally, it is desirable for the plasma generator system to include components, such as gas flow distribution receptacles, with improved useful lives compared to components of conventional plasma generator systems to thereby decrease maintenance costs of such systems. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.